Process for preparing 4, 5-dialkoxy-1, 3-dialkyl-2-imidazolidinones



United States Patent 3,091,617 PROCESS FOR PREPARING 4,5-DIALKOXY-1,3- DlALKYL-Z-IMIDAZOLIDINONES William A. Burris, Rochester; N.Y., assignor to American Cyanamid Company, New York, N.Y., a corporation of Maine No Drawing. Filed Feb. 3, 1961, Ser. No. 86,873 Claims. (Cl. 260-3093) This invention relates to an improved process for preparing 4,5-dialkoxy-1,3-dialkyl-Z-imidazolidinones of the following formula:

H I --(I]H 0R2 0R3 wherein R, R R and R are lower alkyl and inparticular lower alkyl containing from 1- to 4 carbon atoms, as

methyl, ethyl, propyl, isopropyl, butyl, isobutyl and tertiary butyl.

Compounds of this type are believed to be new and are described and claimed in copending application, Serial No. 86,864, filed concurrently herewith, as is a particular and desirable end use for such compounds, namely as cross-linking agents to impart crease resistance and dimensional stability to cellulosic textile materials. In this end use, these compounds are applied to the cellulosic textile material as, for example, cotton in amounts of from between 1 and 25% and in the presence of a curing accelerator, as for example a metal salt such as magneslum chloride, and thereafter dried and cured to a water insoluble state at temperatures of from between250 and 400 F. in accordance with practices well known to those skilled in the art. The finished textile material or product resulting from such a process is characterized by a. resistance to wrinkling, by virtue of the fact that under the curing conditions generally referred to, the alkoxyl groups in the 4 and 5 positions are reacted with the hydroxyl groups of the cellulose molecule whereby a direct ether linkage is formed with said molecule. It is believed that by means of this reaction cross-linking of cellulose fibers occurs.

The conventional method for preparing compounds of the general type referred to above is a two-step process. The first step involves the reaction of a 1,3-dialkylurea with glyoxal under neutral-or slightly alkaline conditions toproduce a 1,3-dialkyl-4,5-dihydroxy-2- imidazolidinone. The second step involves the reaction of the 1,3-dialkyl- 4,5-dihydroxy-Z-imidazolidinone with a lower alcohol under acidic conditions. While this two-step procedure is effective for preparing the compounds of this invention in good quality, the over-all yield for this two-step process is only about 45%. Further, such a procedure requires more processing time and since it is a two-step process it requires additional handling operations and adjustments such as the carrying out of the first step under alkaline conditions and the second step under acidic conditions. These and other disadvantages of such a two-step process render it highly desirable to provide a simple, direct and straightforward one-step process for producing the same end-product.

Accordingly, it is an object of this invention to provide a direct and straightforward process for preparing 4,5- dialkoxy-l,3-dialkyl-2-imidazolidinones of the following general formula:

OR: OR:

as being normal room temperatures.

3 ,0?) 1,6 1 7 Patented May 28, 1 963 where R, R R and R are lower alkyl and preferably lower alkyl containing from 1 to 4 carbon atoms.

In this direct and straightforward process, in which over-all yields of the order of 60% and higher are readily obtained, a 1,3-dialkylurea is reacted in a lower monohydric aliphatic alcohol with glyoX-al under acidic conditions.

While one might expect that the glyoxal would react with the alcohol to form the acetal instead of reacting with the urea, this surprisingly does notoccur. Further,

because of the low pH at which the process is conductedit might normally be expected that a considerable amount of polymeric by-product would form. However, this does not occur.

The 1,3-dialkylureas which may be used include those having alkyl groups containing up to 4 carbon atoms. Such lower alkyl substituted ureas include 1,3-dimethylurea, 1,3-diethylurea, l-methyl-3-ethylurea, 1,3-di-n-propylurea, 1-ethyl-3-n-propylurea, 1,3-diisopropylurea, 1,3- di-n-butylurea, 1,3-di-sec.-butylurea, and the like.

The lower alcohols that may be employed are the lower aliphatic monohydric alcohols having 4 or less carbon atoms, such as methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, and tertiary butyl alcohol.

While it is greatly preferred that the reaction medium be composed entirely of the lower aliphatic monohydric alcohol, in that for the most part optimum results have been achieved thereby, the alcoholic reaction medium may be extended or diluted, in some instances up to as much as 50%, with water and selected organic diluents.

The 1,3-dialkylurea and the glyoxal should normally be reacted on a mole-for-mole basis but preferably a slight excess up :to about 1.15 moles of glyoxal per mole of the 1,3-dialkylurea is employed. Larger excesses of the glyoxal are uneconomical and any unreacted glyoxal in the reaction medium complicates the isolation and purification of the desired end-product. Excesses of the dialkylurea can be employed, but this also is not advisable since unreac-ted dialkylurea would necessarily and desirably have to be separated from the final product.

The reaction between the 1,3-dialkylurea and the glyoxal maybe carried out at normal room temperatures. This is an important advantage of the present process. If desired, the reaction may be run at temperatures of from between 0 and C. at atmospheric pressure with the higher temperatures resulting in a shorter time cycle and the lower temperatures resulting in longer time cycles. It is surprising that the reaction proceeds so well at temperatures as low as 20 to 25 C., which may be construed At temperatures between 20 and 30 C. at atmospheric pressure, the time cycle for the formation of the end products of this invention is normally about 2 to 6 hours.

With regard to determing when the reaction is complete in accordance with the process of this invention, it is for the most part determined empirically for given amounts of material under given reaction conditions.

The process of this invention is preferably carried out at atmospheric pressure, though sub-atmospheric and super-atmospheric pressures may be employed under particular circumstances.

Among the acids which may be employed to catalyze the reaction are the strong mineral acids, such as sulfuric, nitric hydrochloric, phosphoric and perchloric acids, and the strong organic acids, such as oxalic and the toluenesulfonic acids.

The amount of acid catalyst employed is such that the pH of the reaction mixture (as measured with a glass electrode) is less than 4 and preferably less than 2.

After the completion of the reaction and the formation of the desired end-product, it is normally separated from the reaction mixture by conventional means, as for example, distillation. Before exposing the reaction mixture to heat, it is preferable that the acidity therein be neutralized to a pH of between 7 and 10 by the addition of any of the conventional alkaline materials such as sodium hydroxide, potassium hydroxide, sodium carbonate, barium hydroxide, calcium carbonate, calcium oxide and the like.

In order that the present invention may be more fully understood, the following examples are given primarily by way of illustration. No details or enumerations contained therein should be construed as limitations on the present invention except insofar as they appear in the appended claims. -All parts and percentages are by weight unless otherwise specifically designated.

l CH3 CH3 To a solution of 264 parts (3.0 moles) of 1,3-dimethyl- Lurea in 1200 parts of methanol there is added 264 parts (3.45 moles) of 76% glyoxal followed by 28 parts of concentrated sulfuric acid. After stirring overnight at room temperature (20 to 25 (3.), the insolubles are filtered off and the filtrate neutralized with sodium hydroxide until a pH of about 10.0 is obtained. After filtering again, the filtrate is concentrated in vacuo until the residue amounts to about 589 parts. The product is further purified by dissolving in ether, filtering and distilling the solution in vacuo. The purified product amounts to about 323 parts.

' EXAMPLE 2 I 0 CH3 0 CH The procedure of Example 1 is followed substituting an equivalent amount of 1,3-diethylurea for the 1,3-dimethylurea.

EXAMPLE 3 ?H- 1 H OCHa OCH;

The procedure of Example 1 is followed substituting an equivalent amount of 1,3-di-n-butylurea for the 1,3- dimethylurea.

EXAMPLE 4 4,5-Di-Is0pr0poxy-I,3-Dimethyl-Z-Imidazolidinone The procedure of Example 1 is followed substituting an equivalent amount of isopropanol for the methanol.

While the present process has been described as being simply a batch process, it will be readily appreciated that it is capable of conversion to a continuous process by the exercise of the skill of the art.

I claim:

1. A process for preparing a 4,5-dialkoxy-l,3-dialkyl- Z-imidazolidinone which comprises reacting a 1,3-dialkylurea with glyoxal in the presence of a lower alkyl monohydric alcohol and an acid at a pH of less than 4.

2. A process for preparing 4,5-dimethoxy-l,3-dimethyI-Z-irnidazolidinone which comprises reacting 1,3- dimethylurea with glyoxal in the presence of methanol and sulfuric acid at a pH of less than 4.

3. A process for preparing 4,5-dialkoxy-1,3-dialkyl- Z-imidazolidinone which comprises reacting under acidic conditions and at a pH of less than 4 and at a temperature of between 0 and C. at atmospheric pressure a 1,3- dialkylurea with glyoxal in the presence of a lower alkyl saturated monohydric alcohol.

4. A process according to claim 3 in which the 1,3- dialkylurea is 1,3-dimethylurea.

5. A process for preparing a 4,5-dialkoxy-1,3-dialkyl- Z-imidazolidinone which comprises reacting a 1,3-dialkylurea with glyoxal in the presence of a lower alkylmonohydric alcohol and an acid at a pH of less than 2.

References Cited in the file of this patent UNITED STATES PATENTS 2,764,573 Reibnitz et a1 Sept. 25, 1956 3,029,164 Seki et a1 Apr. 10, 1962 FOREIGN PATENTS 962,795 Germany Apr. 25, 1957 717,287 Great Britain Oct. 27, 1954 7 783,051 Great Britain Sept. 18, 1957 OTHER REFERENCES Germany, B 36,767 IVb/ 12 p., Sept. 20, 1956. 

1. A PROCESS FOR PREPARING A 4,5-DIALKOXY-1,3-DIALKYL2-IMIDAZOLIDINONE WHICH COMPRISES REACTING A 1,3-DIALKYLUREA WITH GLYOXAL IN THE PRESENCE OF A LOWER ALKYL MONOHYDRIC ALCOHOL AND AN ACID AT A PH OF LESS THAN
 4. 